Transistor isn't the first game to put its soul into its sword, but it is the first to be quite so transparent about it. Hundreds of action RPGs have already made it clear that the heft and feel of a blade is the focal point for so many loving tweaks and balances, yet Transistor also allows its eponymous weapon to narrate the storyline and play a crucial role in how it unfolds. In the city of Cloudbank, silenced songstress Red stands over the body of a man whose life has been transferred into the perspex skewer that now sticks out of his chest. Draw the sword and start the adventure. Hundreds of games do this stuff too, but none do it in quite this way.

Traditional ideas delivered from an unusual perspective? That was the ethos of Supergiant's debut, Bastion, and it's changed very little here. Bastion buried an old-fashioned hack-and-slash under hand-painted visuals and a lattice of narration delivered in whiskyish, conspiratorial tones. It offered, in the process, a carefully controlled action game that somehow felt like it was running to catch up with you. Compared to such rough-housing, Transistor is a self-conscious study in elegance, yet it still works within an established genre while laying on supplementary ideas. We're deep in action RPG territory, with all the skill bars and cooldowns you might expect, but the story's daringly elliptical in its telling, and the combat dances between real-time and a clever spin on turn-based battling, always flirting, never settling, and drawing its restless energy from an underlying system that encourages tinkering.

At times, Transistor's story may be a little too elliptical. You can race through the campaign and well into New Game Plus before much beyond the basics of the plot have taken shape in your mind. Supergiant enters late and treats you like a grown-up who's really paying attention. Even then, it merely nudges you towards the main themes and a proper understanding of the backstory, laying out a narrative inquest - or at least an intriguing and portentous muddle - in which, with a few exceptions, you can draw your own conclusions.

If Tron had been directed by Klimt or Mucha, it might feel like this. Beneath the looping drums and fuzzy guitars of Darren Korb's wonderfully distanced soundtrack, Transistor's city is Art Nouveau circuitry inlaid with gold leaf and reflective marble and filled with short journeys and bustling connections. Nursing her stolen voice and that talking sword, Red's battling to save this delicate metropolis from a shadowy organisation and a kind of cybernetic parasite called the Process, now busy racing around deleting entire neighbourhoods. A lot of what follows still refuses to untangle itself: as far as I can tell, Transistor seems pretty agitated by the distractions, homogenisation, and faux democracy of social media and perhaps by the strange power of celebrity. It's so varied and complex in its fixations that the whole thing can only be the material from someone's favourite dinner party spiel.

The world's linear, but it's riddled with playful details.

No matter. It's rare to be cast as someone who's famous enough to be papped in the middle of combat, while Cloudbank itself is the kind of place where citizens would rather vote on the colour of the sky than explore the deadlier mysteries that hover around them. For all its artifice, I suspect Transistor ultimately has a human focus. It offers glimpses of the ghosts that end up trapped within our technologies - of the soul pinned between relays and amplifiers.

Technology never looked quite like this, mind. Transistor's world is a glorious, and gloriously confident creation. Brass and stained glass curlicues draw your eyes across isometric battlefields filled with dreamland skyscrapers; at times, the glittering urban sprawl seems to be viewed through a lens smeared with fingerprints. Cloudbank feels like a town inside an old perfume bottle, and Red's an arresting lead. She's both wilful and vulnerable as she drags her massive sword into battle, the tip sending up sparks as it races over the ground. Her enemies range from the Jony Ive turrets and greyhounds of the Process to the Schiele-like aristocrats, all bruised cheekbones and arthritic knuckles, who make up the crew pulling the strings.

And if the narrative falters beneath the weight of hints and feints and the sheer degree of unusual terminology, the narration never does. The tricks that kept Bastion moving are employed with even greater subtlety here; they no longer feel like tricks at all. Although the main events emerge slowly, the minute-to-minute action is enhanced by the soul trapped in that sword - Bastion's voice actor Logan Cunningham again - urging you through the adventure, postulating on what's next, and at times registering surprise at your behaviour. He points out elements of the environment you might have missed, and he comments drily on bad decisions made on the battlefield. "That's one way to do it," he'll deadpan after a particularly graceless exchange of blows. It's subtly instructive to have him around, yet he never succumbs to the fate of so many other video game companions. He never becomes the animated paperclip from MS Word.

Signal and noise

Although similarities with Bastion are easy to spot, the folksy days of the kid are behind you here: Transistor sees a far more troubled narrative unfolding, and a certain distance seems to be part of the package.

This is true even for the relationship between the player and the avatar. Asked to type in a comment at the bottom of an online news story, Red first enters just one word, "Help", before deleting it. It's a moment that delivers a genuine thrill: if you're her, right, why didn't you know she was going to do that?

Lovely stuff, but it's secondary to the game's main appeal. Although you proceed through isometric maps, dipping from one pool of darkness to the next as you work across the city, taking polls, leaving comments beneath online news stories and learning more about the devilish dandies you're up against, the heart of Transistor lies not with exploration but with combat and the systems drawn into its orbit. It's a bold move to make a pretty, even lavish game that's mechanically so sparse. Luckily, what mechanics there are tend to be ingenious.

Functions are initially pretty confusing, but there's a lot of fun to be had making sense of them.

Combat initially seems straightforward as the map sporadically bars your exits to create a snug little arena and then fills the space with luminous white cover that pops from the ground like the bars of a graphic equaliser. You have four active skills you can use against your enemies at any one time - you can swap them out between fights at access points scattered around the maps - and once most of the Process are dispatched under your thudding, candescent blows, you have just seconds to collect the Cells that drop from them before they respawn. Even at this stage there are a lot of traditional concerns to think about. Heavy attacks are slow, fast attacks are light, and the emphasis is on placement as much as rhythm: make use of cover and backstab enemies for greater damage.

Three main tricks elevate things. The first is the idea of turns, which allow you to pause the battle and plan a series of actions which will then be played out in the blink of an eye. It sounds over-powered, but you'll need to be clever, as mere movement eats away at the time you have to play with in a turn, and the relative lengths of specific attacks carry over from standard battling too.

Ideally, you'll want to dash in, strike, and then dash away again so you can hide as your turn recharges and you're left unable to defend yourself. That isn't always possible, though, particularly when the enemies tend to arrive in clever congregations. Ranging from Weeds, plastic tendrils with an area attack and heal, and Cheerleaders, little satellite dishes which can lay down shields, all the way through to the lumbering Jerks and the teleporting Youngladies, Transistor's menagerie of foes are designed to work together, buffing, repairing, and even flanking. As with Bastion, it's not particularly hard to win a fight, but it's hard to win with flair.

Transistor's second trick lies with the framework around the combat system, an RPG build creator which makes just picking your load-out of skills - or to use Transistor's terminology, functions - as much fun as using them. Functions can either be placed into active slots, in which case they'll work as one of your four main attacks, or into upgrade sub-slots to augment specific active functions. In the language of Diablo 3, each skill is also a potential rune for all other skills. Additionally, you can even choose to place functions in passive slots, where they will confer traits like boosted health.

Some of the juxtapositions are a little too neat - a body without a voice paired with a voice without a body.

Supergiant's built a tight system in which almost nothing is wasted and experimentation is encouraged. Purge, for example, spawns a parasite as an active function, but as an upgrade, it applies corruption effects to other functions or gives you a passive counter-blow when struck. Elsewhere, Ping is feeble but fast as a straight-up ranged shot, but when used in an upgrade slot can reduce the time of an attack in a turn or can passively afford you faster movement. There are enough of these functions drip-fed throughout the game with each new level hit to ensure that you can play for hours in Transistor's wonderful laboratory of violence, juggling builds that win enemies over to your side, make you invisible, or summon decoys. Every trip to an access point becomes a chance to try something unlikely, discover that it works, and then promote it to a full-blown tactic until the next unlikely discovery comes along.

Such a mix-and-match approach requires deft balancing from the designers, and you can tell because that balance isn't always quite right. Jaunt, used as an upgrade, for example, allows you to spam an attack when waiting for a turn to recharge. It's such a powerful advantage that it can often reduce the elegant combat to button-mashing - and the game never truly provides a reason for you to stop using it.

This is where Transistor's final trick comes in, however. Defeat in combat won't initially lead to your death. Instead, it will remove the function you've been relying on the most and keep it out of rotation for a while. It's a simple but startling penalty, forcing you away from a favoured load-out and back to experimentation. Like the best restrictions, it ultimately frees players. It frees them from themselves and the ruts that the min-maxing approach can cause. Elsewhere, alongside new functions and ways to use them, each level reached also includes Limiters, which offer XP boosts from combat in exchange for harsher battle conditions. It's another Bastion idea, but it really clicks here, mounted in a rare game that genuinely expands in creative scope as it gets harder.

Towards the end of the campaign you'll meet enemies who can disrupt your turns.

Together, the whole thing clicks, in fact, especially when the cooldown that follows a turn moves the game away from a real-time flow and dials up the attendant panic. I love games that will make you meaningfully bear the cost of a mistake, and I love games that let you tinker until you've created a build that's really weird, but that still works in a world designed to encourage weird thinking.

If there's a problem, in fact, it's that functions are still only starting to present their stranger pleasures by the time the game comes to an end somewhere around the five-hour mark. I'm not arguing that Transistor should be longer, as I'd rather have a short game with this much poise and density of detail than a long game that runs out of ideas. The issue, though, is that Transistor hasn't quite run out of ideas.

Price and availability

Available on PC and PlayStation 4 on 20th May: £14.99

When you head back for another playthrough, however, you'll find a game that's eager to greet you, New Game Plus not only carries over character progression, but also juggles encounters around to keep them interesting, while a range of additional combat challenges will allow you to continue tinkering within some energising restrictions.

That those challenges are housed in a weird trans-dimensional coastal getaway where you can kick a physics-enabled beach ball about or lie in a hammock is just one of many unusual things to enjoy about Transistor. Enjoy the artful approach to science-fiction, enjoy the hoops Supergiant's jumped through to position you in the right place to engage with its combat, and you can even enjoy the very fact that the game often struggles to get its deeper messages across. After all, if the developer had something straightforward to say, it might not have had to make a game in the first place.